We hope to determine whether any clinical characteristics of patients with acute psychoses will predict the likelihood of their responding to lithium as opposed to neuroleptic treatment. The results should be of value to the clinician treating such patients, and also of theoretical interest in clarifying the nature of psychotic symptomatology. We propose to study a group of subjects with acute psychoses, who will have varying amounts of affective and cognitive symptomatology, and varying levels of premorbid functioning. They will be randomly assigned to either lithium or chloropromazine for a three-week, double-blind trial. In analyzing the results, we will attempt to find subgroups of the patient population, or combinations of clinical factors, for which the response to the two drugs is different. In a (nonblind) follow-up study, the longer-term therapeutic or adverse effects of the two drugs will be compared.